Photographic film



May 16, 1939. E. 1.. BAXTER 2,158,173

PHOTOGRAPHIC FILM Fi led Sept. 17, 1936 Sunmcf CoAmJ Mm Cawws: Esme Am) 8mm: nc Pia/N.

--TIFCELLULOSEESTEPANDSYNTHETICPESIN.

PEDORGREENSIDEOFRQPER LACKSIDEOFPAPER.

v MLW ATTORNEYS.

Paten ed May 16, 1939 PATENT OFFICE PHOTOGRAPHIO FILM Ernest L. Baxter, Rochester, N. Y., assiznor to- Eashnan Kodak Company, a corporation of New Jersey Rochester, N. Y.,

Application September 17, 1936, Serial No. 101,282

2 Claims. (01. 95-9 invention relates to photographic material and particularly to protective coatings on paper used with photographicfilm.

When sensitive photographic material, such as 5 photographic roll film or cut fllmis distributed to the consumer, a backing of paper or opaque material is placed over the sensitive surface and around the outside of the sensitive material. In

the case of roll films the protective material is rolled up with the sensitive material, while in the case of cut films -or film packs the protective material may be placed between the sensitive sheets. In either case the protective material comes in contact with the sensitive surface and must be coated with a material having suitable properties. Among these properties are non-desensitizing action for the sensitive surface, im-

permeability to moisture, and protective action against fog and mottle of the sensitive surface.

Among the materials which have been used to coat the protective backingused to wrap the sensitive material, are the cellulose organic esters.-

The use of synthetic resins for this purpose has also been suggested. Each of these materials lacks some of the properties desired. The cellulose esters afford adequate protection against moisture, but poor protection against fog and mottle of the sensitive surface. on the other hand afford adequate protection against fog and mottle, but are not always resistant.'- It is, therefore, an object of the present invention to provide a protective backing for sensitive photographic material which will protect the ma- 3; terial against moisture, fog, mottle and. de-

, sensitizing action.

This object is accomplished by coating the protective backing of paper or other opaque material with a mixture of a cellulose organic acid 0 ester and a synthetic resin.

In the accompanying drawing, Fig. I is a plan view of a roll film having a protective backing made according to my invention.

Fig.2 is a sectional view of a protective back.-

ing material made according to my invention.

' The invention will now be described with particular reference to the accompanying drawing.

In Fig. l the spool l0 carries a sheet of protective,material ll having a black surface I! on the inside of the roll, and av layer (I! of mixed cellulose organic acid ester and synthetic resin on the 'outside of the roll. A piece of sensitive film l4v is laid onthe s'in'face l2 and is rolled up with the protective backing material ll.; wh en Synthetic resins I water stead of using one part resin to two parts cellulose rolled up in this way the sensitive surface I! comes into contact with the coated surface l3. of the backing material.

Fig. 2 illustrates a backing paper made according to my invention. In the enlarged sectional 5 mly bonded together 0 The following specific examples illustrate com- 15 positions of the cellulose ester and synthetic resin that may be used in coating the backing paper according to my invention.

ester, 1 may use as much as 4 parts resin to one part cellulose ester or as. little as 1 part resin to four parts cellulose ester. Any suitable solvent material for the cellulose ester and resin used may be employed. I. prefer to use a cellulose 4 mixed organic acid ester such as the acetate propionate or butyrate having a higher acyl content (propionate or butyrate) of from 14% to 18%, although this may be varied from 10% to 40%. The total acyi should' be at least 42%. 4

Among the synthetic resins which may. be used according to my invention, a great-manymatcrials are available. These include the polyvinyl esters, such as polymerized vinyl acetate which is kn Wii, for example, under, the tradename Gelvafl'. the preparation of which is.described in the D; 8. Patents Nos. 1,241,738} 1,586,803 and 1,710,826.- A further type of resin which may be Example I Parts 2 Cellulose acetate propionatene. l.. 2 Polymerized vinyl acetate (Gelva) 1 Solvent mixture acetone and 30% ethylene dichloride) 24 2 Example II Parts Cellulose acetate propionate 2 Polystyrene resin (Victron) 1- Solvent mixture (70% acetone and 30% *30 ethylene dichloride) 24 The proportions of the material stated in the above examples are illustrative only and may be varied overconsiderable range. For example, in- 35 used is the polyvinyl acetal type. These resins 5- I In are condensation products of partially or completely hydrolyzed polyvinyl acetate and an aldehyde such as formaldehyde, acetaldehyde, or butyraldehyde and are known as polyvinyl acetals. They are sold under various tradenames suchas Formvar and Alvar", the preparation of which is described in British Patent No. 351,082 and in U. S. Patents Nos. 1,955,068 and 1,990,399. A still further type of resin which I may use are the alkyd resins, which are condensation products of a polybasic acid and a polyhydroxy alcohol. An example of this type of resin is "Glyptal, which is a condensation product of glycerin and phthalic acid or phthalic anhydride. A still further type of resin is the polystyrene group such as the resin known as .Victron, sold by the Naugatuck Chemical Company.

It is to be understood that my invention is limited only by the scope of the appended claims.

What I claim is:

1. A photographic element comprising a film having a light-sensitive layer on one surface thereof, and adjacent the opposite surface thereof a protective material comprising a paper support coated, on its surface opposite that which is in contact with the film, with a mixture of a cellulose mixed organic acid ester having a total acyl content of at least 42% and a. polyvinyl ester resin in such proportions that when the ester and resin layer comes in contact with the light-sensitive layer, said last-mentioned layer is adequately protected against moisture, fog, and mottle.

2. A photographic roll film comprising a film having a light-sensitive layer on one surface thereof, and adjacent the opposite surface thereof a protective material comprising a paper support coated, on its surface-opposite that whichis in contact with the film, with a mixture of cellulose acetate propionate having a. total aoyl con- 

